Actually I believe not honouring is correct in this case because it isn't as per T&C unless you really twist the T&C
They made an offer that said I would receive something by booking through a valid Accor call center. Then I did not receive it because of a definition of an Accor call center that makes sense only to them.
I believe most reasonable people would agree that an Accor hotel's reservation call centre qualifies as an Accor call centre. So I am not sure why you believe this is as per T&C.
Whenever we call this particular property, whether an "official" Accor call centre handles the call or an "unofficial" Accor call centre (hotels own) handles the call is transparently handled on the basis of time of day.
Central reservations vs Hotel reservations desks are a distinction without a difference and is nothing but a totally nonsensical annoying 'gotcha'.
But if you are anticipating problems, maybe chatting up the desk at checkin may help resolve the problem?
The property is as confused by this as I am. They are not sure since when they ceased to be an official Accor channel since they are very much an Accor property! I received all the points and stay credit, I just din't get anything else because "I did not book via an official Accor channel"